Advanced wireless devices may have multiple radios (e.g., WWAN, WLAN, WPAN, GPS/GLONASS, etc.) that operate on the same, adjacent, or harmonic/sub-harmonic frequencies. However, some combinations of radios can cause co-existence issues due to interference between the respective frequencies. In particular, when one radio is actively transmitting at or close to the same frequency and at a same time that another radio is receiving, the transmitting radio can cause interference to (i.e., de-sense) the receiving radio. For example, same-band interference may occur between Bluetooth (WPAN) and 2.4 GHz WiFi (WLAN); adjacent band interference between WLAN and LTE band 7, 40, 41; harmonic/sub-harmonic interference may occur between 5.7 GHz ISM and 1.9 GHz PCS; and an intermodulation issue may occur between 7xx MHz and a GPS receiver.
Analog interference cancellation (AIC) cancels interference between a transmitter radio and a receiver radio by matching gain and phase of a wireless coupling path signal and in a wired AIC path, as shown in FIG. 1, where dt is a transmitted signal from a transmitter (aggressor) radio 102, and hc is a coupling channel (wireless coupling path signal) from the transmitter radio 102 to a receiver (victim) radio 104. AIC 106 attempts to cancel the impact of the coupling channel hc as reflected via the negative sign on the output of AIC 106. AIC may be implemented with respect to RF (radio frequency), baseband, or both RF/baseband.